Methods of solidifying low-boiling-point hydrocarbon and handling the same, and regeneration thereof

ABSTRACT

Disclosed are a method of solidifying a low-boiling-point hydrocarbon, wherein the low-boiling-point hydrocarbon (including hydrocarbons which are gaseous at ordinary temperature) is brought into contact with a metal salt of an aliphatic carboxylic acid, and if necessary a high-boiling-point hydrocarbon, suspended in water, to form a solid aggregate substance, a method of handling the low-boiling-point hydrocarbon, wherein the solid aggregate substance is stored or transported, and a method of regenerating the low-boiling-point hydrocarbon, wherein the solid aggregate substance is decomposed by opening or heating, to obtain the low-boiling-point hydrocarbon. According to the methods, a wide variety of gaseous and highly volatile liquid hydrocarbons can be safely and easily solidified without using harmful reagent, and during storage, transportation, etc., the gaseous hydrocarbons and highly volatile liquids can be handled as a solid material. Further, by releasing under atmospheric pressure at room temperature or by heating if necessary, the original hydrocarbons can be easily obtained.

FIELD OF THE INVENTION

The present invention relates to a method of solidifyinglow-boiling-point hydrocarbons (e.g., hydrocarbons that are liquid witha high vapor pressure at ordinary temperature, as well as hydrocarbonsthat are gaseous at ordinary temperature), a method of regenerating thissolidified product into low-boiling-point hydrocarbons in the originalstate, and a method of handling low-boiling-point hydrocarbons byutilizing these methods.

BACKGROUND OF THE INVENTION

As the scale of the petrochemical industry is enlarging year by year,organic compounds are produced and consumed in a large amount, andfurther, natural gas is used in a large amount. In this connection,pollution and accidents threatening the existence of mankind and livingcreatures, such as environmental pollution, water pollution, pollutionof the ocean by tanker accidents; fires, and explosion accidents, occurfrequently and worldwide, and the handling of organic compounds,including petrochemical materials, is an important issue. One cause forsuch pollution and accidents is mistakes made by people or inadequatesafety measures, such as incomplete combustion, leakage, and release.Another and essential cause is, as a matter of course, that many of theorganic compounds that have caused pollution and accidents are highlyvolatile liquids or gases. In particular, a basic requirement in thepetroleum chemistry and the natural gas chemical industry is thatgaseous organic substances can be handled safely at ordinarytemperature.

In addition, the method of handling organic compounds used as industrialraw materials during storage and transportation, as well as coststhereof, is greatly influenced by the gaseous state of most such organiccompounds. This is a fundamental problem in modern petrochemistry,including utilization of natural gas, and this is not an issue that canbe solved by switching to carbochemistry or to utilization of solidfuels, such as charcoal.

As to this problem, it is proposed that gaseous organic compounds shouldbe handled in a safer state during storage, transportation, etc.Attempts at this include handling an organic gas, such as methane, as astable hydrate, i.e. methane hydrate (generally gas hydrate), byinclusion thereof into a cage structure formed by hydrogen bonds ofwater molecules, but it cannot be said that this attempt has beencompleted as practically usable techniques. Further, methane hydrate(gas hydrate) essentially requires several times or more water moleculesthan organic gases, and thus a very large amount of unnecessary watermust be handled simultaneously.

In the case of hydrogen, for example, a hydrogen-occlusion alloy, whichcan reversibly occlude and release a hydrogen gas repeatedly, has beenproposed, but for organic compounds, no such substance capable ofreversible occlusion and release has been found.

Accordingly, it is desired that low-boiling-point liquid hydrocarbonsand gaseous hydrocarbons can be handled as safe solids during storage,transportation, etc., while the original hydrocarbons can be taken outfrom the solid when used. It is considered that the requirements forsuch solidified materials of hydrocarbons are, for example, that theymust be (1) repeatedly usable, (2) chemically relatively stable, and (3)safe and harmless, because their use in a large amount is estimated, andthey are less dangerous even if they are discharged to the outside ofthe storage system.

Proposed methods of solidifying organic compounds that are liquid atordinary temperature are described in JP-A-55-75493 (“JP-A” meansunexamined published Japanese patent application) and JP-A-59-142274,but these methods involve utilizing hydrophilic groups in the compounds,thereby incorporating water and solidifying the compounds. Further,there is no description therein of a method of solidifying hydrocarbonsthat are gaseous or highly volatile liquid at ordinary temperature, andthe solids described in these literatures cannot be reused whennecessary by decomposition, to take out only hydrocarbons therefrom.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a methodof realizing reversible solidification of low-boiling-point hydrocarbons(including hydrocarbons that are gaseous at ordinary temperature) byutilizing materials satisfying the conditions as described above; thatis, an object of the present invention is to provide a method ofsolidifying low-boiling-point hydrocarbons, a method of taking outlow-boiling-point hydrocarbons in the original state from the solidifiedproduct, and a method of handling low-boiling-point hydrocarbons byusing these methods.

Other and further objects, features, and advantages of the inventionwill appear more fully from the following description, taken inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the result of differential scanningcalorimetry (DSC) of the white waxy solid aggregate substance inExample 1. Exothermal peaks in a cooling step are shown above, andendothermic peaks in a heating step are shown below.

FIG. 2 is an enlarged view of a peak of n-butane in the graph of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors studied the interaction based on van der Waalsforce in water between n-paraffins and a surfactant having a long-chainalkyl group, and found that the surfactant can easily form a macroscopicaggregate substance with short-chain n-paraffins, and also fixlow-boiling-point and low-melting-point n-paraffins, to solidify them.Further, we found that other hydrocarbons can also be solidified. Afterextensive studies based on this finding, the present invention was made.

That is, the present invention provides:

(1) A method of solidifying a low-boiling-point hydrocarbon, wherein thelow-boiling-point hydrocarbon is brought into contact with a metal saltof an aliphatic carboxylic acid and a high-boiling-point hydrocarbonsuspended in water, to form a solid aggregate substance (referred tohereinafter as the first aspect of the invention);

(2) A method of handling a low-boiling-point hydrocarbon, wherein thesolid aggregate substance obtained by the solidification methoddescribed in the above (1) is stored or transported (referred tohereinafter as the second aspect of the invention);

(3) A method of regenerating a low-boiling-point hydrocarbon, whereinthe solid aggregate substance obtained by the solidification methoddescribed in the above (1) is decomposed by heating, to obtain thelow-boiling-point hydrocarbon (referred to hereinafter as the thirdaspect of the invention);

(4) A method of solidifying a gaseous hydrocarbon, wherein a metal saltof an aliphatic carboxylic acid, and a hydrocarbon that is a gas atordinary temperature, are dissolved, emulsified, or suspended in water,to form a solid aggregate substance of the hydrocarbon (referred tohereinafter as the fourth aspect of the invention);

(5) A method of handling a gaseous hydrocarbon, wherein the solidaggregate substance obtained by the solidification method described inthe above (4) is stored or transported (referred to hereinafter as thefifth aspect of the invention); and

(6) A method of regenerating a gaseous hydrocarbon, wherein the solidaggregate substance obtained by the solidification method described inthe above (4) is decomposed by opening or heating, to obtain the gaseoushydrocarbon (referred to hereinafter as the sixth aspect of theinvention).

In the first to third aspects of the invention described above, thelow-boiling-point hydrocarbons forming a solid aggregate substance meanhydrocarbons which are gaseous or liquid having a high vapor pressure atordinary temperature (20° C.). The high-boiling-point hydrocarbons andlow-boiling-point hydrocarbons are compounds composed of carbon atomsand hydrogen atoms, and they are preferably free from oxygen atoms,nitrogen atoms, sulfur atoms, etc. The solid aggregate substance in thefirst to third aspects of the invention is formed in water from a metalsalt of an aliphatic carboxylic acid and the hydrocarbon describedabove, and the formed aggregate substance does not contain water. Thesolid aggregate substance formed in the first aspect of the invention ismaintained stably in a solid state, in a closed vessel generally at roomtemperature (preferably 10 to 35° C., more preferably 20 to 25° C.) orless, preferably at room temperature or less, and low-boiling-pointhydrocarbon can be taken out from the aggregate substance upondecomposition by heating preferably at 70° C. or more.

In the fourth to sixth aspects of the invention described above, thegaseous hydrocarbons forming a solid aggregate substance mean compoundscomposed of carbon atoms and hydrogen atoms, which are gaseous atordinary temperature (20° C.), and these compounds are preferably freefrom oxygen atoms, nitrogen atoms, sulfur atoms, etc. The solidaggregate substance of the gaseous hydrocarbon in the fourth to sixthaspects of the invention is a white and gel-like or rice cake-likemacroscopic aggregate substance consisting of a metal salt of analiphatic carboxylic acid and a hydrocarbon, which is a molecularaggregate substance aggregated due to the van der Waals force betweenalkyl chains of the metal salt of an aliphatic carboxylic acid and thehydrocarbon. This aggregate substance is maintained stably in a solidstate, in a closed vessel generally at room temperature or less, fromwhich the original gaseous hydrocarbon can be taken out by opening theclosed vessel or by heating the aggregate substance in the closedvessel.

The metal salt of an aliphatic carboxilic acid used in the presentinvention (referred to hereinafter as a metal salt of a carboxylic acid)is not particularly limited, and it is a metal salt of a carboxylic acidthat is preferably straight-chain or branched or that has unsaturatedbond(s) in the middle of a carbon chain. The number of carbon atoms inthe metal salt of a carboxylic acid is preferably 4 to 22, particularlypreferably 11 to 18, in the first to third aspects of the invention, orpreferably 9 to 20, more preferably 12 to 18, in the fourth to sixthaspects of the invention. The type of the metal is not particularlylimited. Generally, any metal salts contained in metallic soap,preferably a sodium salt, can be used.

Specifically, examples of the metal salt of a carboxylic acid which canbe used in the present invention include sodium tridecanoate, sodiummyristate, sodium pentadecanoate, sodium palmitate, sodiumheptadecanoate and sodium stearate. In addition, sodium oleate can alsobe mentioned as a usable salt in the fourth to sixth aspects of theinvention.

First, the first to third aspects of the invention are described.

According to the first to third aspects of the invention describedabove, in a suspension containing the metal salt of a carboxylic acidand the high-boiling-point hydrocarbon suspended in water, thelow-boiling-point hydrocarbon is brought into contact with them, tosolidify. The high-boiling-point hydrocarbons in the first to thirdaspects of the invention are solid or liquid having a relatively not solarge vapor pressure (that is, those not easily evaporated) at ordinarytemperature and having preferably a boiling point of 60° C. or more.Preferably, they are saturated or unsaturated aliphatic hydrocarboncompounds (which may be either straight-chain or branched) containing 6to 18 carbon atoms, or aromatic hydrocarbon compounds containing 6 to 9carbon atoms. Specific examples include n-hexane, n-heptane, n-decane,2,2,4-trimethylpentane, 1-decene, benzene, toluene, xylene, ethylbenzeneand cumene.

Generally, the high-boiling-point hydrocarbon forms an aggregatesubstance more easily as the number of carbon atoms therein isdecreased. However, in consideration of the easiness of separating theorganic compounds from each other in the form of the formed aggregatesubstance of the high-boiling-point hydrocarbon and thelow-boiling-point hydrocarbon to the original pure hydrocarbons, thehigh-boiling-point hydrocarbon having a larger number of carbon atomscan be more easily separated. Accordingly, a practically suitablecombination is used by selecting, e.g. high-boiling-point hydrocarbonswhich are different in boiling temperature by 60° C. or more fromlow-boiling-point hydrocarbons to be solidified.

The low-boiling-point hydrocarbons that are solidified in the first tothird aspects of the invention and that are capable of regeneration fromthe solidified product are organic compounds preferably having a boilingpoint of 40° C. or less, which are gaseous at ordinary temperature, orliquid that is evaporated easily due to their high vapor pressure(highly volatile liquid) at ordinary temperature. These are saturated orunsaturated aliphatic hydrocarbon compounds containing preferably 2 to 5carbon atoms, more preferably 3 to 5 carbon atoms, which may bestraight-chain or branched. For example, when a metal salt ofpentadecanoic acid is used, all hydrocarbons containing 3 or 4 carbonatoms, and hydrocarbons containing 5 carbon atoms that are liquid atroom temperature but evaporated easily due to their extremely high vaporpressure, can be solidified, and then regenerated from their solidifiedproduct.

Specifically, example of the low-boiling-point hydrocarbons which can beused in the first to third aspects of the invention include propane,n-butane, isobutane, n-pentane, branched pentane, ethylene, acetylene,propylene and butenes. These can be treated alone or in combination oftwo or more in a mixed system, but a distinct feature of this inventionis that these are treated alone and can be taken out alone in a purestate, according to necessity.

In the first aspect of the invention, a suspension prepared bysuspending the high-boiling-point hydrocarbon and the metal salt of acarboxylic acid in water is used. In this suspension, the low-boilinghydrocarbon is further brought into contact with them, thereby thelow-boiling hydrocarbon is easily incorporated into the resultantaggregate substance, and the macroscopic aggregate substance can beformed under conditions near to those for the high-boiling hydrocarbon.Depending on the type of the low-boiling hydrocarbons, they can besolidified by leaving them at room temperature in a short period oftime. This can be considered that hydrocarbon chains of thehigh-boiling-point hydrocarbon are first fixed via van der Waals forceto alkyl chains of the metal salt of a carboxylic acid, and thelow-boiling-point hydrocarbon is then fixed to these alkyl chains of thehigh-boiling-point hydrocarbon, to form an aggregate substance. Thisaggregate substance is formed in water, but upon formation, it isseparated completely from water, and thus water is not contained in theaggregate substance.

Embodiments for formation of the macroscopic aggregate substanceaccording to the method of the first aspect of the invention are notparticularly limited. For example, there are:

(1) A method of adding the hydrocarbon high in boiling point understirring, to an aqueous solution containing the metal salt of acarboxylic acid dispersed therein, followed by adding the desiredlow-boiling-point hydrocarbon thereto;

(2) A method of simultaneously stirring the metal salt of a carboxylicacid, the high-boiling-point hydrocarbon and water, followed by addingthe desired low-boiling-point hydrocarbon thereto; and

(3) A method of simultaneously stirring and mixing the four components,that is, the high-boiling-point hydrocarbon, the low-boiling-pointhydrocarbon, the metal salt of a carboxylic acid, and water.

For example, the formation of a solid aggregate substance ofhydrocarbons according to the method of the first aspect of theinvention is conducted by heating a system comprising the metal salt ofa carboxylic acid, the high-boiling-point hydrocarbon and water, todissolve the metal salt of a carboxylic acid completely, then mixingthem uniformly, and blowing the low-boiling-point hydrocarbon in agaseous state. Water used is preferably pure water. Stirring isconducted preferably until the metal salt of a carboxylic acid isuniformly dissolved, emulsified or suspended. Generally, after thecompletion of blowing the low-boiling-point hydrocarbon and leaving themixture at room temperature, then immediately a macroscopic aggregatesubstance composed of the high-boiling-point hydrocarbon, thelow-boiling-point hydrocarbon and the metal salt of a carboxylic acid isformed and separated completely from water. Depending on the metal saltof a carboxylic acid used and the type of high-boiling-point andlow-boiling-point hydrocarbons to be solidified, their solidifiedproduct may be formed more reliably, by gradually cooling the mixtureafter being left and then keeping it at a temperature lower than roomtemperature, or by heating the mixture at about 80° C. or cooling it atabout 0° C. during stirring.

In the solidification method in the first aspect of the invention, themolar ratio of the metal salt of a carboxylic acid/the high-boilinghydrocarbon is preferably 1/10 to 1/1000, more preferably 1/10 to 1/500,and the molar ratio of the metal salt of a carboxylic acid/water ispreferably 1/50 to 1/50000, more preferably 1/100 to 1/5000.

The amount of low-boiling-point hydrocarbons added thereto is preferably1/10 to 1/1000, more preferably 1/10 to 1/500, in terms of the molarratio of the metal salt of carboxylic acid/low-boiling-pointhydrocarbon.

In the manner as described above, the total amount of the metal salt ofcarboxylic acid and high-boiling-point hydrocarbon and of thelow-boiling-point hydrocarbon allowed to be coexistent therewith inwater can be practically formed into a solid macroscopic aggregatesubstance.

The formed macroscopic aggregate substance can be also separated fromwater, by a usual means such as filtration or centrifugation, or bypicking the aggregate substance up from water. This solid aggregatesubstance after formed is very stable, and it can generally be stablymaintained even if the aggregate substance formed by heating or keepingit at low temperature is returned to room temperature. For example, anaggregate substance of sodium pentadecanoate, the high-boiling-pointhydrocarbons and the low-boiling-point hydrocarbons is very stablegenerally up to about 60° C.

Now, the fourth to sixth aspects of the invention are described.

The hydrocarbons that are solidified in the methods of the fourth tosixth aspects of the invention and that are capable of regeneration fromtheir solidified product may be those that are gaseous at ordinarytemperature. These materials are preferably saturated or unsaturatedaliphatic hydrocarbons containing preferably 4 or less carbon atoms,more preferably 2 to 4 carbon atoms, which may be straight-chain orbranched. For example, when sodium pentadecanoate is used, all saturatedhydrocarbons containing 3 or 4 carbon atoms, and unsaturatedhydrocarbons containing 2 to 4 carbon atoms (excluding ethylene), can besolidified, and from this solid product, the hydrocarbons in theoriginal state can be regenerated.

Specifically, examples of the gaseous hydrocarbons which can be used inthe methods of the fourth to sixth aspects of the invention includepropane, n-butane, isobutane, acetylene, propylene and butenes. Thesecan be treated alone or in combination of two or more in a mixed system,but a distinct feature of this invention is that these can be treatedalone and taken out alone in a pure state, according to necessity.

In the fourth to sixth aspects of the invention, the method ofdissolving, emulsifying or suspending hydrocarbons and a metal salt ofcarboxylic acid in water is not particularly limited. Feeding of gaseoushydrocarbons at ordinary temperature, into water containing a metal saltof carboxylic acid suspended therein, can be conducted in a usualmanner. For example, mention is made of a method of introducing gaseoushydrocarbons under high pressure and a method of feeding liquefiedhydrocarbons.

Examples of concrete embodiments for forming the macroscopic aggregatesubstance according to the fourth aspect of the invention include thefollowings:

(1) Gaseous hydrocarbons are introduced under high pressure (preferably0.5 to 5 MPa) into a pressure-resistant vessel containing a metal saltof carboxylic acid and water, then the metal salt of carboxylic acid iscompletely dissolved by heating, and the mixture is sufficiently stirredand left at room temperature.

(2) A pressure-resistant vessel containing a metal salt of carboxylicacid and water is cooled (preferably at −20 to −85° C.), then gaseoushydrocarbons are introduced into the vessel and liquefied, the vessel issealed and heated to dissolve the metal salt of carboxylic acidcompletely, and the mixture is sufficiently stirred and left at roomtemperature.

(3) Hydrocarbons liquefied by pressurization are introduced directly,into a pressure-resistant vessel containing a metal salt of carboxylicacid and water, then the vessel is sealed and heated to dissolve themetal salt of carboxylic acid completely, and the mixture issufficiently stirred and left at room temperature.

Heating for dissolving the metal salt of carboxylic acid is conductedfor about 5 to 30 minutes at 30 to 95° C. depending on the type of themetal salt of carboxylic acid. Water used is preferably pure water.Stirring is conducted preferably until the metal salt of carboxylic acidis uniformly dissolved, emulsified or suspended. Generally, afterstirring is finished, the mixture is left at room temperature forseveral hours to 1 day, thereby a macroscopic aggregate substancecomprising the gaseous hydrocarbons and the metal salt of carboxylicacid is formed and separated from water, to float on water.

Depending on the metal salt of carboxylic acid used and the type ofhydrocarbons to be solidified, the solidified product may be formed morereliably, by At gradually cooling the mixture after being left and thenkeeping it at a temperature lower than room temperature, or by heatingit with boiling water before stirring.

In the solidification method in the fourth aspect of the invention, themolar ratio of the metal salt of carboxylic acid/the gaseous hydrocarbonis preferably 1/10 to 1/1000, more preferably 1/10 to 1/200, and themolar ratio of the metal salt of carboxylic acid/water is preferably1/50 to 1/50000, more preferably 1/100 to 1/2000.

In the manner as described above, an almost total amount, excluding alittle amount of gaseous hydrocarbons remaining in an upper part of thevessel, of gaseous hydrocarbons allowed to be coexistent in water withthe metal salt of carboxylic acid, can be practically formed into asolid macroscopic aggregate substance.

The formed macroscopic aggregate substance can also be separated fromwater, by a usual separation means such as filtration, or by removingwater through a lower drainage hole in the vessel in a method of pushingwater out by utilizing the gas pressure of gaseous hydrocarbonsremaining in an upper part of the vessel. This solid aggregate substanceafter formed is stable, and it can generally be maintained stably in aclosed vessel even if the aggregate substance formed by heating or bykeeping it at a low temperature is returned to room temperature. Thesolid aggregate substance formed in the method of the present inventionmay be evaporated at ordinary temperature and ordinary pressure, in anopened state (i.e. not in a closed vessel). To prevent this evaporation,the solid aggregate substance is stored in a vessel which can be closed.It is not necessary that this closed vessel is a pressure-resistantvessel, and any ordinarily used closed vessels can be used withoutparticular limitation. For example, an aggregate substance of sodiumpentadecanoate and gaseous hydrocarbons is generally stable at 50° C. orless when maintained in a closed vessel.

A solid aggregate substance formed by the method in the first aspect ofthe invention, for example, an aggregate substance of sodiumpentadecanoate and high-boiling-point and low-boiling-pointhydrocarbons, is initiated to be decomposed generally at 65° C. or moreand completely decomposed upon heating at 80° C. or more. Thetemperature at which the aggregate substance is completely decomposed isvaried depending on the type of the metal salt of carboxylic acid andthe hydrocarbons, but the macroscopic aggregate substance is liquefiedupon heating generally at 70° C. or more, or in some cases at 50 to 80°C., thereby it is separated into two layer solutions consisting of themetal salt of carboxylic acid and the high-boiling-point hydrocarbon,respectively. During this separation, the low-boiling-point hydrocarbonis completely evaporated and separated so that by collecting this gas,the original low-boiling-point hydrocarbon can be obtained. On the otherhand, the high-boiling-point hydrocarbon in the original state can alsobe regenerated and obtained by a usual means, e.g. using a difference indensity to separate the solution into the high-boiling-point hydrocarbonand the metal salt of carboxylic acid.

If the solid aggregate substance formed by the method in the fourthaspect of the invention described above is placed in an opened state byopening the closed vessel, the aggregate substance is decomposed whileboiling generally at 20 to 30° C. under ordinary pressure, and thehydrocarbons contained in the solid aggregate substance is completelygasified and separated so that by recovering this gas, the originalgaseous hydrocarbons can be obtained.

In addition, the aggregate substance can also be decomposed by heatingin a closed state. For example, an aggregate substance of sodiumpentadecanoate and hydrocarbons is initiated to be decomposed generallyat 50° C. or more and completely decomposed by heating at 70° C. ormore. The temperature at which the aggregate substance is completelydecomposed is varied depending on the type of the metal salt ofcarboxylic acid and hydrocarbons, but the macroscopic aggregatesubstance is decomposed by heating generally at 70° C. or more, or at 50to 80° C. depending on the case, and the gaseous hydrocarbons arecompletely gasified and separated.

The separated and recovered metal salt of carboxylic acid can berepeatedly used.

In the present invention, the low-boiling-point hydrocarbons (includinggaseous hydrocarbons) can be handled in a solid form as described above,during transportation, storage, etc.

In the second aspect of the invention wherein a solid aggregatesubstance of low-boiling-point hydrocarbons is handled, the solidaggregate substance is handled preferably by keeping it at roomtemperature or less. In addition, this solid aggregate substance ishandled preferably by keeping it in a closed vessel. For use oflow-boiling-point hydrocarbons by release from their solid aggregatesubstance, the aggregate substance is heated and decomposed as describedabove, and the gasified components are collected.

In the fifth aspect of the invention wherein a solid aggregate substanceof gaseous hydrocarbons is handled, the solid aggregate substance ishandled by keeping it in a closed vessel, preferably at room temperatureor less. For use of gaseous hydrocarbons by release from their solidaggregate substance, the aggregate substance is placed in an openedstate by opening the closed-state, or the aggregate substance is heatedin the closed vessel, as described above, thereby the aggregatesubstance is decomposed, and the components thus gasified are collected.

According to the method of the present invention, a wide variety ofgaseous hydrocarbons and highly volatile liquid hydrocarbons can besafely and easily solidified, by utilization of the intermolecular vander Waals force between the hydrocarbons and the metal salt of acarboxylic acid (and high-boiling-point hydrocarbons, if necessary), andthey can thus be converted, without using any harmful reagent, into sucha form as to be safely stored, transported, etc. According to thepresent invention, since gaseous hydrocarbons or highly volatile liquidhydrocarbons can be handled in the form of solid during storage,transportation, etc., accidents and environmental pollution, such asleakage and ignition of the organic compounds, can be effectivelyprevented and transportation costs etc. can also be reduced. Further,the original hydrocarbons can be easily obtained, by releasing theirsolidified product under atmospheric pressure at room temperature, or byheating it if necessary, as well as the metal salt of a carboxylic acidcan also be repeatedly used. The method of this invention as describedcan also be practiced even in an industrial scale.

Hereinafter, the present invention is described in more detail byreference to the following examples, which however are not intended tolimit the invention.

EXAMPLES Example 1

10⁻³ mole of sodium pentadecanoate, 2×10⁻¹ mole of n-heptane and 1 moleof pure water were weighed, then placed in a glass vessel, sealed,heated to 85° C., and stirred with a vortex mixer, to form a uniformemulsion. The emulsion was returned to room temperature, and 2×10⁻² moleof n-butane was blown into it and left at room temperature for 10minutes, thereby a white macroscopic aggregate substance appeared whilethe liquid phase was composed exclusively of colorless and transparentpure water. It was filtered to give 22 g of a stable (white waxy) solidaggregate substance.

The result of this white waxy solid aggregate substance in differentialscanning calorimetry (DSC) is shown in FIG. 1. In this graph, exothermalpeaks in a cooling step (that is, at a decreasing temperature) are shownabove (upper side) and endothermic peaks in a heating step (that is, atan increasing temperature) are shown below (lower side). The followingpeaks at decreasing and increasing temperatures show respectively thecrystallization and melting of the following compounds: a major peak at−93° C. at both decreasing and increasing temperatures shows thecrystallization and melting of n-heptane; a peak at −148° C. at adecreasing temperature and a peak at −144° C. at an increasingtemperature, n-butane; a peak at −36° C. at a decreasing temperature anda peak at −0° C. at an increasing temperature, an aggregate substance ofn-butane and sodium pentadecanoate; and a peak at about 55° C. at adecreasing temperature and complex peaks at 47° C. to about 70° C. at anincreasing temperature, an aggregate substance of nheptane and sodiumpentadecanoate. FIG. 2 shows an enlargement of a peak of n-butane inFIG. 1. As can be seen from the results in FIGS. 1 and 2, n-butane ismaintained certainly in the white waxy solid aggregate substance.

Then, this aggregate substance was heated to 80° C. and gently shaken,thereby 10⁻³ mole of sodium pentadecanoate, 2×10⁻¹ mole of n-heptane(liquid) and 2×10⁻² mole of n-butane (gas) were obtained.

Example 2

The solidification procedure was carried out in the same manner as inExample 1, except that 2×10⁻¹ mole of ndecane was used in place ofn-heptane, thereby, after being left for a whole day at roomtemperature, 31 g of a stable solid aggregate substance of n-decane andn-butane was obtained. This aggregate substance could be used toregenerate sodium pentadecanoate, n-decane (liquid) and n-butane (gas)by the similar heating decomposition and subsequent separation as inExample 1.

Example 3

The solidification procedure was carried out in the same manner as inExample 1, except that 2×10⁻¹ mole of 2,2,4-trimethylpentane was used inplace of n-heptane, thereby 25 g of a stable solid aggregate substanceof 2,2,4-trimethylpentane and n-butane was obtained. This aggregatesubstance could be used to regenerate sodium pentadecanoate,2,2,4-trimethylpentane (liquid) and n-butane (gas) by the similarheating decomposition and subsequent separation as in Example 1.

Examples 4 to 6

The solidification procedure was carried out in the same manner as inExample 1, except that 2×10⁻² mol propane was used in place of n-butane,thereby 22 g of a stable solid aggregate substance of n-heptane andpropane was obtained. This aggregate substance could be used toregenerate sodium pentadecanoate, n-heptane (liquid) and propane (gas)by the similar heating decomposition and subsequent separation as inExample 1. Using propylene or 1-butene, in place of propane, the samesolidification and regeneration procedures as described above wereconducted, thereby a stable solid aggregate substance was obtained ineach case and it could be well used to regenerate the original materialsby heating.

Examples 7 to 12

The solidification procedure was carried out in the same manner as inExample 1, except that sodium stearate was used in place of sodiumpentadecanoate, thereby 22 g of a stable solid aggregate substance ofn-heptane and n-butane was obtained. This aggregate substance could beused to regenerate sodium stearate, n-heptane (liquid) and n-butane(gas) by the similar heating decomposition and separation as inExample 1. Using sodium laurate, sodium tridecanoate, sodium myristate,sodium palmitate or sodium heptadecanoate, in place of sodium stearate,the same solidification and regeneration as described above wereconducted, thereby a stable solid aggregate substance was obtained ineach case and it could be used well for regeneration by heating.

Example 13

2×10⁻⁴ mole (52.8 mg) of sodium pentadecanoate and 0.2 mol (3.6 ml) ofpure water were weighed, placed in a pressure-resistant glass vessel andcooled to −85° C. with dry ice/ethanol. n-Butane gas was introduced froma butane gas bomb via a thin tube into the pressure-resistant glassvessel. The butane was immediately liquefied. After 1.12×10⁻² mole (0.9ml=650 mg) of the liquefied butane was introduced into the pressureresistant glass vessel, the vessel was closed, returned once to roomtemperature and heated to 72° C., and the sodium pentadecanoate was thuscompletely dissolved, vigorously shaken and stirred, thereby a uniformwhite suspension containing a large amount of white bubbles, consistingof sodium pentadecanoate, pure water and n-butane, was obtained. Afterleft at room temperature, the solution in a lower part immediatelybecame colorless and transparent, and after several hours, about 10white particles with a diameter of 2 to 3 mm appeared in this colorlessand transparent solution. The number of white particles was increasedwith the lapse of time to about 100, and the particles were mutuallyaggregated, to give, after several hours, 650 mg of a white, single andmacroscopic self-aggregate substance composed of sodium pentadecanoateand n-butane, which was floating on the pure water.

This macroscopic self-aggregate substance was very stable in a closedsystem for a long period of time in the coexistence of water even at aroom temperature of 30° C. or more, but it was gradually decomposed at atemperature over 40° C. When released to atmospheric pressure, boilingof the self-aggregate substance was immediately initiated and it wascompletely decomposed.

When separated from water by declining the glass vessel, the macroscopicaggregate substance showed an increase in thermostability in a closedsystem and it could be stored stably for a long period of time at 50° C.or less. If the aggregate substance was kept at 50° C., itsdecomposition was initiated, but the decomposition immediately stoppedin a closed system, and the majority of its white mass was kept stablyas it was. More than half of the white mass was kept stably even at 60°C. At 70° C., it was completely decomposed, and sodium pentadecanoatedissolved in water as well as butane gas (partially liquefied in aclosed system) was quantitatively obtained.

In this example, the composition after decomposition was 50 mg of sodiumpentadecanoate and 600 mg of butane.

Example 14

10⁻⁴ mole (23.6 mg) of sodium tridecanoate and 0.1 mole (1.8 ml) of purewater were weighed and placed in a pressure-resistant glass vessel, and0.02 mole (1.9 ml) of liquefied butane was introduced into thepressure-resistant glass vessel in the same manner as in Example 1. Thevessel was sealed, returned once to room temperature and heated to 60°C., and the sodium tridecanoate was thus completely dissolved,vigorously shaken and stirred, thereby a uniform white suspensionconsisting of sodium tridecanoate, pure water and n-butane was obtained.After left this overnight at room temperature, 1.3 g of a whiteself-aggregate substance composed exclusively of sodium tridecanoate andn-butane, floating on the pure water, was obtained.

Then, this aggregate substance was separated from the water, heated to70° C. in a closed system and gently shaken, to give 10⁻⁴ mole of sodiumtridecanoate and 0.018 mole of n-butane gas.

Examples 15 to 17

The solidification procedure was carried out in the same manner as inExample 14, except that 10⁻⁴ mole of sodium myristate, sodium palmitate,or sodium stearate was used in place of sodium tridecanoate, thereby 1.3g of a stable solid aggregate substance of n-butane was obtained,respectively. Each of this aggregate substance could be used toregenerate n-butane gas by the similar decomposition by releasing orheating and subsequent separation as in Example 13 or 14.

Examples 18 to 20

The solidification procedure was carried out in the same manner as inExample 14, except that 0.02 mole of propylene, 1-butene or isobutanewas used in place of n-butane, thereby 1 to 1.3 g of a stable solidaggregate substance was obtained, respectively. Each of this aggregatesubstance could be used to regenerate about 0.015 mole of gaseouspropylene, 1-butene or isobutane by the similar decomposition byreleasing or heating and subsequent separation as in Example 13 or 14.

Having described our invention as related to the present embodiments, itis our intention that the invention not be limited by any of the detailsof the description, unless otherwise specified, but rather be construedbroadly within its spirit and scope as set out in the accompanyingclaims.

What is claimed is:
 1. A method of solidifying a gaseous hydrocarbon,comprising dissolving, emulsifying or suspending in water a metal saltof an aliphatic carboxylic acid and a hydrocarbon that is gaseous atordinary temperature (20° C.), thereby forming a solid aggregatesubstance of the hydrocarbon.
 2. The method of solidifying a gaseoushydrocarbon according to claim 1, wherein the molar ratio of the metalsalt of an aliphatic carboxylic acid/the gaseous hydrocarbon is 1/10 to1/1000, and the molar ratio of the metal salt of an aliphatic carboxylicacid/the water is 1/50 to 1/50000.
 3. A method of regenerating a gaseoushydrocarbon, comprising heating the solid aggregate substance obtainedby the solidification method in claim 1, to decompose said solidaggregate substance, thereby obtaining the gaseous hydrocarbon.
 4. Amethod of handling a gaseous hydrocarbon, comprising storing ortransporting the solid aggregate substance obtained by thesolidification method in claim
 1. 5. The method of handling a gaseoushydrocarbon according to claim 4, wherein the solid aggregate substanceis handled with keeping in a closed vessel.
 6. A method of regeneratinga gaseous hydrocarbon comprising opening a closed vessel which comprisesthe solid aggregate substance obtained by the solidification method inclaim 1, to decompose said solid aggregate substance, thereby obtainingthe gaseous hydrocarbon.
 7. The method of regenerating a gaseoushydrocarbon according to claim 6, wherein the solid aggregate substanceis released under atmospheric pressure.